Metallic hollow profiles are frequently and effectively connected by way of gusset plates which are arranged between the profiles and are subsequently connected thereto by welds. For weight reasons, in motor vehicle manufacturing, use is generally made of hollow profiles consisting of aluminium, and the gusset plates are likewise manufactured from aluminium.
During the formation of conventional welds, a high amount of heat is applied, causing distortion of the assembly. The dimensional accuracy is negatively influenced. In order to produce flat and therefore stable connections, holes have to be made in the plates in order to form plug or slot welds. Furthermore, during the welding, there are sputters which have to be removed in a complicated manner from the surfaces.
By way of friction-stir welding, or indirect friction-stir welding, plates consisting of aluminium may be connected to one another with a low application of heat. The plates are placed one above the other and the friction-stir welding tool is placed onto the upper side of the one plate under pressure and moved along a designated connecting line. A connection is produced. However, use in the case of hollow profiles is not possible.
German Patent Publication No. DE 10 2010 018 504 A1 discloses a method for producing a hollow profile using friction-stir welding. A semi-finished component consisting of an aluminium alloy is connected along a connecting line by way of a weld formed by friction-stir welding. During the welding, a counter holder which supports the welding zone from the lower side is introduced into the profile.
The welding of two plates lying in one plane along the contact line thereof by way of friction-stir welding is described by German Patent Publication No. DE 10 2010 003 742 A1.
The connection of two plates adjacent to each other in a plane on a hollow profile is illustrated in Japanese Patent Publication No. JP 2004 261 859 A. By way of a tool, the plates are welded to each other along the border, which forms a gap, by way of friction-stir welding, at the same time, a metal strip is also placed into the gap.
The production of a hollow profile part by joining together two shaped parts and by connecting the shaped parts along the joining line by way of friction-stir welding is illustrated in Japanese Patent Publication No. JP 2001 233 208 A.
A method for producing a low-twist frame structure by lap-welding is illustrated in German Patent Publication No. DE 100 11 593 A1. A T-shaped gusset piece which is inserted into the tube ends to be connected serves here as a connecting element for three tubes. The tube end region overlapping the inserted gusset piece is friction-stir welded by way of a revolving tool such that the tube material may be connected to the material of the gusset piece in the context of a friction-stir weld.
Japanese Patent Publication No. JP 11 226 759 A also describes the connection of profile parts by way of friction-stir welding. The parts which are to be connected to one another are oriented with respect to one another, and a pressure piece absorbing the compressive forces occurring during the friction-stir welding is welded at the same time in the contact region of the parts.